Microscopy System

ABSTRACT

The invention relates to a microscopy system for representing an object that can be placed on an object plane ( 1 ) of the microscopy system, the latter comprising a representation system ( 26 ) containing several optical elements for providing at least one optical representation path ( 2   a,    2   b,    2   c,    2   d ). According to one embodiment of the invention, the optical elements comprise a plurality of optical lenses ( 4 - 8, 11, 13, 14 ), through which the optical representation path(s) ( 2   a - 2   d ) pass(es) in sequence and which represent the object plane ( 1 ) in an intermediate image (P). The optical lenses ( 4 - 8, 11 ) are configured in such a way that the representation of the object plane ( 1 ) in the intermediate image (P) is reduced a maximum 0.9 times, preferably a maximum 0.8 times, preferably a maximum 0.6 times, with 0.5 times being the preferred maximum reduction.

The present invention relates to a microscope system for imaging anobject that can be placed in an object plane of the microscope system,the system comprising the features of the preambles of the independentclaims 1, 3 and 19.

The microscope system comprises at least one imaging system thatprovides at least one optical imaging path for imaging a field of viewof the object plane.

Microscope systems of this sort are used, for example, in medicaltechnology as surgical microscopes, to observe an object placed in anobject plane.

Such an optical microscope is, for example, known from the Germanlaid-open patent application DE 103 00 925 A1.

With respect to surgical microscopes it is generally desirable toachieve a compact construction, i.e. a small overall height and a smallvolume. The reason for this is that the surgical microscope should notunduly restrict accessibility to a patient by an attending physicianduring surgery.

As shown in FIG. 8, a surgical microscope usually consists of a Keplertelescope 82, a zoom system 83 and a main objective 84. The Keplertelescope in FIG. 8 comprises a binocular tube. The Kepler telescope 82,the zoom system 83 and the main objective 84 are arranged in seriesalong the respective optical imaging paths 85A, 85B, guided by theseelements and provide imaging an object (not shown in the Figure) that isplaced in an object plane 81. Afocal interfaces are provided in-betweenthe Kepler telescope 82, the zoom system 83 and the main objective 84,in which afocal interfaces the optical imaging paths are each imaged toinfinity, to provide a modular structure of the surgical microscope. Asshown in FIG. 8, such microscopes are frequently built as stereoscopicmicroscope systems. In stereoscopic microscope systems, at least twooptical imaging paths 85A and 85B are guided such that the opticalimaging paths include a stereoscopic angle α, different from zero, inthe object plane 81.

Furthermore, a beam splitting prism, which is not shown in FIG. 8, isfrequently provided between the Kepler telescope and the zoom system, toprovide an optical path for co-observation.

It is a disadvantage of conventional surgical microscopes that they havea large overall height and a large volume, dependent on a provided totalmagnification.

Therefore, it is an object of the present invention to provide amicroscope system wherein the imaging system necessary to provide thedesired total magnification has an especially compact structure.

The above object is achieved by a microscope system comprising thecombination of the features of the independent claims 1, 3 and 19.Preferred embodiments are defined in the dependent claims.

According to a first embodiment, the above object is achieved by amicroscope system for imaging an object that can be placed in an objectplane of the microscope system, wherein the microscope system comprisesan imaging system containing several optical elements for providing atleast one optical imaging path. The several optical elements comprise aplurality of optical lenses, through which the at least one opticalimaging path passes in sequence, and which image the object plane in anintermediate image. The optical lenses are configured in such a way thatthe representation of the object plane in the intermediate image isdemagnified to a maximum of 0.9 times, preferably to a maximum of 0.8times, further preferably to a maximum of 0.6 times, and especially to amaximum of 0.5 times. In this respect, “demagnified to a maximum of 0.9times” means that the representation of the object plane in theintermediate image is demagnified by 0.1 (i.e. 10%) or more.

Consequently, the microscope system is capable of firstly imaging anobject placed in the object plane in a demagnified way in theintermediate image. This intermediate image can then be magnified bysubsequent optics, until a desired total magnification is achieved. Dueto the demagnified representation of the object placed in the objectplane in the intermediate image, it is possible to build the opticsfollowing the intermediate image in an especially compact way, such thatthe microscope system has an especially compact structure when comparedto a microscope system known from the prior art providing the same totalmagnification.

It can be advantageous that the several optical elements of the imagingsystem provide at least one pair of optical imaging paths, which includea first stereoscopic angle in the object plane, wherein the opticalimaging paths include a second stereoscopic angle in the intermediateimage, and wherein a ratio of the first stereoscopic angle in the objectplane to the second stereoscopic angle in the intermediate image issmaller than 0.9 and especially smaller than 0.8, and further especiallysmaller than 0.6.

Consequently, the stereoscopic angle in the intermediate image isenlarged, when compared to the stereoscopic angle in the object plane,and as a result the optical imaging paths can be separated with ease bythe optics following the intermediate image, not withstanding thedemagnification of an object placed in the object plane. Therefore adesired stereoscopic impression is guaranteed.

According to a further embodiment, which can be combined with the firstembodiment, the above object is achieved by a microscope system forimaging an object that can be placed in an object plane of themicroscope system, wherein the microscope system comprises an imagingsystem containing several optical elements, to provide at least one pairof optical imaging paths that include a first stereoscopic angle in theobject plane. The several optical elements contain a plurality ofoptical lenses through which the at least one pair of optical imagingpaths passes in sequence, and which image the object plane in anintermediate image. The optical imaging paths include a secondstereoscopic angle in the intermediate image. A ratio between the firststereoscopic angle in the object plane to the second stereoscopic anglein the intermediate image is smaller than 0.9 and especially smallerthan 0.8, and further especially smaller than 0.6.

This enlargement of the stereoscopic angle in the intermediate image, incomparison to the stereoscopic angle in the object plane, facilitates aseparation of the optical imaging paths by optical elements imaging theintermediate image. Consequently, the microscope system can be built inan especially compact way, as the optical imaging paths diverge to ahigher degree in comparison to the prior art.

According to an embodiment, the optical imaging paths can commonlytraverse the optical lenses. In this case, the optical imaging paths canbe guided in the lenses such that the intermediate image is arrangedin-between two regions, in which a distance of stereoscopic axes of theoptical imaging paths from an optical axis defined by the lenses,respectively, is maximized. It is not necessary that the optical axisruns along one single straight line, but it is even possible that theoptical axis is folded. The stereoscopic axes are defined by therespective centers of the at least two (stereoscopic) optical imagingpaths for one object point of the object that can be placed in theobject plane, which object point corresponds to the center of therepresentation caused by the microscope system.

According to a further embodiment, the at least one optical imaging pathcan be guided in the lenses in a way that the intermediate image isarranged in-between two regions, in which a diameter of a beam bundleguided by the at least one optical imaging paths, respectively, ismaximized.

Furthermore, a first set of optically effective surfaces of lenses canbe arranged between the intermediate image and the first region of thetwo regions, in which at least one of a distance of stereoscopic axes ofthe optical imaging path from the optical axis and a diameter of a beamof light guided by the at least one optical imaging path, respectively,is maximized. This first region is arranged between the intermediateimage and the object plane. Further, a second set of optically effectivesurfaces of lenses can be arranged between the intermediate image andthe second region of the two regions, and a third set of opticallyeffective surfaces of lenses can be arranged between the first regionand the object plane. The surfaces of one optical lens may belong to oneset or else to different sets.

It can be advantageous if a ratio of the total focal length (sum of thefocal lengths) of the optically effective surfaces of the first set tothe total focal length of the optically effective surfaces of the secondset is at least 1.1, and especially at least 1.2, and further especiallyat least 1.4.

It can be further advantageous if a ratio of the total focal length (sumof the focal lengths) of the optically effective surfaces of the firstset to the total focal length of the optically effective surfaces of thethird set is between 0.2 and 0.6, and especially between 0.3 and 0.5,and further especially 0.4.

Further advantages can be achieved if a ratio of the total focal lengthof the optically effective surfaces of the second set to the total focallength of the optically effective surfaces of the third set is between0.1 and 0.6, and especially between 0.2 and 0.5, and further especially0.3.

The ratios defined above of the total focal length of the sets ofoptically effective surfaces can provide a demagnified representation ofan object that can be placed in the object plane into the intermediateimage in an especially easy way. It can be further advantageous if theratio of the respective distances of the stereoscopic axes of theoptical imaging paths to the optical axis in the first region to therespective distances of stereoscopic axes of the optical imaging pathsto the optical axis in the second region is not more than 1.1 andespecially not more than 1.2 and further especially not more than 1.4.

Consequently, the optical imaging paths in the first region between theintermediate image and the object plane are separated to a larger extentthan in the second region behind the intermediate image. Due to thereduction of this distance it is possible to build the microscope systemin an especially compact way.

To facilitate a modular structure of the microscope system, the lensesmay be adapted to represent the optical imaging paths, at least in oneof the regions in which at least one of the distance of stereoscopicaxes of the optical imaging paths to the optical axis and the diameterof a beam bundle guided in at least one optical imaging path ismaximized, to infinity.

According to an embodiment, the imaging system may comprise first,second, third and fourth mirror surfaces, for deflecting the at leastone optical imaging path, wherein the at least one optical imaging pathis reflected in sequence on the first mirror surface, the second mirrorsurface, the third mirror surface, and the fourth mirror surface. Anespecially compact structure of the microscope system can be achieved bythis multiple deflection of the optical imaging paths.

The first and fourth mirror surfaces may include, relative to oneanother, an angle of between 80° and 100° and especially 90°, and thesecond and third mirror surfaces may include, relative to each other, anangle of between 80° and 100° and especially 90°, and the third andfourth mirror surfaces may include, relative to each other, an angle ofbetween 80° and 100° and especially 90°. Consequently, the mirrorsurfaces provide a Porro-system of the second kind.

According to an embodiment the imaging system provides at least one pairof optical imaging paths that include a stereoscopic angle in the objectplane, and the imaging system contains a first subsystem containingseveral optical lenses arranged along one common optical imaging path,which optical lenses are commonly traversed by both optical imagingpaths of the at least one pair of optical imaging paths.

At least one of the second, third and fourth mirror surfaces can bearranged between optical lenses of the first subsystem along a foldedoptical axis of the first subsystem.

To vary at least one of the magnification of representation of theobject that can be placed in the object plane, and a working distance ofthe microscope system, it can be advantageous if at least two lenses ofthe first subsystem can be displaced relative to each other along theoptical imaging paths guided by the lenses.

According to an embodiment, the imaging system comprises a secondsubsystem containing several optical lenses, each of which are traversedby only one optical imaging path of the at the least one pair of opticalimaging paths. The beams, or rays, which are respectively guided by theoptical lenses of the second subsystem, define the course of the opticalimaging paths in the optical lenses of the first subsystem, and thus thecourse of the stereoscopic axes.

To further adjust the magnification of the representation of the objectthat can be placed in the object plane, it may be advantageous if atleast two lenses of the second subsystem can be displaced relative toone another along the common optical imaging path.

According to a further embodiment the above object is achieved by amicroscope system for imaging an object that can be placed in an objectplane of the microscope system, which microscope system comprises atleast one imaging system for providing at least one pair of opticalimaging paths, which include a stereoscopic angle in the object plane.This embodiment may be based on the embodiments described above. Theimaging system comprises a first subsystem containing several opticallenses that are commonly traversed by both optical imaging paths of theat least one pair of optical imaging paths. Furthermore, the imagingsystem comprises a second subsystem containing several optical lenseswhich respectively are traversed by only one optical imaging path of theat least one pair of optical imaging paths. At least two lenses of thefirst subsystem and at least two lenses of the second subsystem aredisplaceable along one common optical imaging path relative to eachother, to respectively adjust the magnification of the representation ofthe object that can be placed in the object plane.

Consequently, the adjustable magnification of the representation of theobject that can be placed in the object plane, which magnification isachieved by the microscope system, can be split up within the microscopesystem in two zoom systems arranged in series, wherein the first zoomsystem is arranged in the first subsystem and the second zoom system isarranged in the second subsystem.

It may provide benefits if the microscope system further comprises alighting system containing an optical lighting path for illuminating theobject plane.

A microscope system having the features described above is especiallysuitable for use as a stereoscopic microscope, and especially as asurgical microscope, due to its compact structure.

In the following, preferred embodiments of the present invention will bedescribed with reference to the enclosed Figures. In the Figures, alikeor similar reference signs are used to refer to like or similarelements.

FIG. 1A schematically shows an optical path through an arrangement ofbasic elements of an imaging system of a microscope system according toa first preferred embodiment of the present invention, wherein thearrangement is unfolded in one plane;

FIG. 1B schematically shows a perspective view of a spatial arrangementof the basic elements of the imaging system of FIG. 1A;

FIG. 2A schematically shows an optical path through optical lenses ofthe imaging system shown in FIG. 1A at a larger scale;

FIG. 2B schematically shows an optical path through optical lenses thatmay be used in the imaging system according to the first embodiment asan alternative to FIG. 2A;

FIG. 3 provides as exemplary comparison between the sizes of lenses ofthe microscope system according to the present invention and thecorresponding lenses of a conventional microscope system;

FIG. 4 shows an arrangement of lenses that may be alternatively used inthe microscope system of FIG. 1A;

FIG. 5 shows different operating states of a further arrangement oflenses that can be used as an alternative in the microscope system ofFIG. 1A;

FIG. 6 shows different operating states of a further arrangement oflenses that alternatively may be used in the microscope system of FIG.1A;

FIG. 7 schematically shows an optical path of an imaging system of amicroscope system according to a second embodiment of the presentinvention; and

FIG. 8 schematically shows the general structure of a microscope systemaccording to the prior art.

A preferred first embodiment of the present invention is described inthe following, referring to FIGS. 1A and 1B.

FIG. 1A schematically shows an optical path through an arrangement ofbasic elements of an imaging system 26 of a microscope system accordingto the preferred first embodiment of the present invention, wherein thearrangement is unfolded in one plane.

The microscope system according to the first preferred embodimentcomprises an optical imaging system 26 that provides a pair of opticalimaging paths 2 a and 2 b. Alternatively, the imaging system 26 canprovide a single optical imaging path, or more than one pair of opticalimaging paths.

The optical imaging paths 2 a and 2 b intersect pairwise, in the opticalplane 1. Stereoscopic axes of the optical imaging paths intersectincluding a first stereoscopic angle α1. Thus, the microscope systemforms a stereoscopic microscope. Dependent on the operating state of themicroscope system, the first stereoscopic angle α1 in FIG. 1A rangesfrom 4° to 10°. However, the present invention is not restricted to thisrange of angles. It is generally sufficient if the stereoscopic angle isdifferent from 0°.

The imaging system 26 consists of a first optical subsystem T1 and asecond optical subsystem T2, each subsystem T1 and T2 consisting ofseveral optical elements.

The first optical subsystem T1 consists of the following elements thatare arranged along one common optical axis A: a first optical deflectionelement having a first optical mirror surface 3; first, second, third,fourth and fifth optical lenses, 4, 5, 6, 7 and 8; a second opticaldeflection element having a second optical mirror surface 9; a thirdoptical deflection element having a third optical mirror surface 10; asixth optical lens 11; a fourth optical deflection element having afourth optical mirror surface 12; and seventh and eighth optical lenses13 and 14. The lenses 4, 5, 6, 7, 8, 11, 13 and 14 of the firstsubsystem T1 are commonly traversed by both optical imaging paths 2 aand 2 b.

The optical imaging paths 2 a and 2 b are reflected, and thus deflected,in sequence on the first mirror surface 3, the second mirror surface 9,the third mirror surface 10 and the fourth mirror surface 12. It isevident that even the common optical axis A of the first subsystem T1,that is defined by the lenses 4, 5, 6, 7, 8, 11, 13 and 14, is deviatedmultiple times by the mirror surfaces 3, 9, 10 and 12.

It is also apparent from FIG. 1B that normal vectors of the planesdefined by the first mirror surface 3 and the fourth mirror surface 12,as well as normal vectors of the planes defined by the third mirrorsurface 10 and the fourth mirror surface 12, as well as normal vectorsof the planes defined by the second mirror surface 9 and the thirdmirror surface 10, relative to each other, include a constant angle of90°. However, the angle may differ from 90° and especially range between60° and 110° and preferably between 80° and 100°.

This arrangement of the first to fourth mirror surfaces 3, 9, 10 and 12optically operates in the same way as a Porro-system of the second kind.

This means that the first to fourth mirror surfaces 3, 9, 10 and 12cause both images reversal and permutation of the pupils. Furthermore,an especially compact structure of the imaging system 26 is achieved bythis arrangement of the mirror surfaces 3, 9, 10 and 12, due to themultiple folding of the optical imaging paths 2 a and 2 b.

In this first preferred embodiment the optical lenses 4 to 8 and 11 areconfigured such that the object plane 1 is imaged demagnified to afactor of 0.36 (which means demagnified by 64%) in an intermediate imageP. In this respect, the intermediate image P is a plane that isoptically conjugated to the object plane 1 (this plane may even becurved). The intermediate image P is arranged between the sixth andseventh lens 11, 13, and in more detail between the sixth lens 11 andthe fourth mirror surface 12. It is emphasized that the presentinvention is not restricted to a reduction of the object plane to 0.36times in the intermediate image P, or to the above arrangement of theintermediate image P. It is generally sufficient if the object plane isimaged demagnified to a maximum of 0.9 times, and especially to amaximum of 0.8 time, and further especially to a maximum of 0.6 times,and further especially to a maximum of 0.5 times in the intermediateimage P.

Considering that the basic object of a microscope system is to provide amagnified representation of an object that can be placed in the objectplane 1, it may be surprising that, in the microscope system accordingto the first preferred embodiment of the present invention, the objectplane 1 is not imaged magnified, but demagnified (decreased) in theintermediate image P. However, significant advantages are achieved bythis feature, as will be described in the following.

In the intermediate image P the optical imaging paths 2 a and 2 bintersect including a second stereoscopic angle α2, wherein a ratio ofthe first stereoscopic angle α1 in the object plane 1 to the secondstereoscopic angle α2 in the intermediate image P is smaller than 0.9and preferably smaller than 0.8, and especially preferably smaller than0.6. In the present case, the second stereoscopic angle α2 is 90.6°, andthe stereoscopic angle at the object-side α1 is 73°. Thus, this ratio is0.36. Furthermore, an afocal interface AF1 or AF2, respectively, isarranged between the third optical lens 6 and the fourth optical lens 7,as well as succeeding the eight optical element 14, wherein the opticalpresentation paths 2 a and 2 b are focused to infinity in the afocalinterfaces. The provision of the afocal interfaces AF1 and AF2 providesfor a modular structure of the imaging system 26 of the microscopesystem. In FIG. 2 a, the afocal interface AF1 is shown schematically atan enlarged scale.

As an alternative to the arrangement of the intermediate image P betweenthe afocal interfaces AF1 and AF2, the optical imaging paths 2 a and 2 bmay be guided in the lenses 4 to 8, 11, 13 and 14, respectively, suchthat the intermediate image P is arranged between two regions, in whicha distance Da, Db of stereoscopic axes of the optical imaging paths 2 aand 2 b to the optical axis A defined by the lenses 4 to 8, 11, 13 and14, respectively, is maximized.

Such a region AF1′ is schematically shown in FIG. 2B. In FIGS. 1A and 1Bthese regions correspond to the afocal interfaces AF1 and AF2.

As is also evident from FIGS. 2A and 2B, a diameter Sa, Sb of a beambundle guided in the optical beam paths 2 a and 2 b respectively has amaximum in the regions mentioned above, which correspond to the afocalinterfaces AF1 and AF2 in FIGS. 1A and 1B.

These afocal interfaces AF1 and AF2 and the regions mentioned above,respectively, enable grouping of the optical lenses 4 to 8, 11 and 14 ofthe first subsystem T1 of the first preferred embodiment, shown in FIGS.1A and 1B, into three sets G1, G2, and G3.

The first set G1 comprises the lenses 7, 8 and 11, having the opticallyeffective surfaces 7 a, 7 b, 7 c, 8 a, 8 b, 8 c, 11 a, 11 b and 11C, andare arranged between the intermediate image P and a first one AF1 of thetwo afocal interfaces, this first afocal interface AF1 being arrangedbetween the intermediate image P and the object plane 1. The total focallength of the first set G1 is 115.3 mm in the first embodiment.

The second set G2 is arranged between the intermediate image P and theother second afocal interface AF2 and comprises the lenses 13 and 14containing the optically effective surfaces 13 a, 13 b, 14 a, 14 b and14 c. The total focal length of the second set G2 is 82.3 mm in thefirst embodiment.

The third set G3 it arranged between the first afocal interface AF1 andthe object plane 1 and comprises the lenses 4, 5 and 6 having theoptically effective surfaces 4 a, 4 b, 4 c, 5 a, 5 b, 6 a, 6 b and 6 c.The total focal length of the third set D3 is 322.5 mm in the firstembodiment.

By using the sets G1, G2 and G3 defined above it is possible to identifypreferred ratios for the refraction powers of the optically effectivesurfaces of the lenses of the respective sets. In this respect, anoptically effective surface is defined as a surface of a lens that istraversed by optical imaging paths 2 a and 2 b, having a radius ofcurvature of a maximum 10⁴ mm and especially a maximum 5×10³ mm andfurther especially a maximum of 10³ mm. It is evident that a lens maybelong to two different sets at the same time, if its optical surfacesbelong to different sets.

For the compact structure of the inventive microscope system, which isdesired by the underlying problem for a total magnificationcorresponding to that of the prior art, it has been found to beespecially advantageous if a ratio of the total focal length (i.e. thesum of the focal lengths) of the optically effective surfaces 7 a, 7 b,7 c, 8 a, 8 b, 11 a and 11 b of the lenses 7, 8 and 11 of the first setG1 to the total focal length of the optically effective surfaces 13 a,13 b, 14 a, 14 b and 14 c of the lenses 13 and 14 of the second set G2is at least 1.1 and especially at least 1.2 and further especially atleast 1.4. In the first embodiment shown in FIG. 1A this ratio is 1.40.This ratio may even be denoted as the afocal magnification factor of thereversal system. The shown reversal system has the property that itcomprises the optically effective elements between the first opticalinterface AF1 and the second optical interface AF2, that it causes imagereversal and permutation of the pupils, and that it comprises theintermediate image P. This afocal magnification factor significantlycontributes to the required total magnification of the microscopesystem.

An important requirement for the compact structure for the microscopesystem, that is desired according to the underlying object, is,respectively, the reduction of the representation of an object that canbe placed in the object plane 1 in the intermediate image P, and theenlargement of the second stereoscopic angle α2 in the intermediateimage P, in comparison to the first stereoscopic angle α1 in the objectplane 1.

It has been found to be especially suitable if a ratio of the totalfocal length of the optically effective surfaces 7 a, 7 b, 7 c, 8 a, 8b, 11 a and 11 b of the lenses 7, 8 and 11 of the first set G1 to thetotal focal length of the optically effective surfaces 4 a, 4 b, 4 c, 5a, 5 b, 6 a, 6 b and 6 c of the lenses 4, 5 and 6 of the third set G3 isbetween 0.2 and 0.6, and especially between 0.3 and 0.5, and furtherespecially 0.4. In the first embodiment, shown in FIG. 1A, this ratio is0.36. This ratio may even be termed the reproduction scale for an objectthat can be placed in the object plane 1 into the intermediate image P.

Further advantages can be achieved if a ratio of the total focal lengthof the optically effective surfaces 13 a, 13 b, 14 a, 14 b and 14 c ofthe lenses 13 and 14 of the second set G2, to the total focal length ofthe optically effective surfaces 4 a, 4 b, 4 c, 5 a, 5 b, 6 a, 6 b and 6c of the lenses 4, 5 and 6 of the third set G3, is between 0.1 and 0.6and especially between 0.2 and 0.5, and more especially 0.3. In thefirst embodiment, shown in FIG. 1A, this ratio is 0.255. This ratioconsists of the loupe magnification of the object plane 1 to infinity ofVLO=250 mm/(focal length of the lenses 4,5,6) that is caused by thelenses 4, and 6 and the loupe magnification of the intermediate image Pto infinity of VLO=250 mm/(focal length of the lenses 13,14) that iscaused by lenses 13 and 14.

The ratio of the respective distances Da, Db of stereoscopic axes of theoptical imaging paths 2 a and 2 b from the optical axis A in the firstafocal interface AF1, respectively in the first region, to therespective distances of stereoscopic axes of the optical imaging pathsfrom the optical axis A in the second afocal interface AF2, respectivelyin the second region, is maximally 1.1 and preferably maximally 1.2 andfurther preferably 1.4. With respect to the distances of thestereoscopic axes from the optical axis defined by the respective lensesin the respective afocal interfaces, respectively regions, reference iscomplementarily made to FIGS. 2A, 2 b.

The ratios defined above are all suitable to contribute to at least oneof a demagnified representation of the object plane 1 in theintermediate image P and a magnification of the second stereoscopicangle α2 in the intermediate image P in comparison to the firststereoscopic angle α1 in the object plane 1. However, it is notobligatory that all of the above ratios are fulfilled at the same time,as long as at least one of a demagnified representation of the objectplane 1 into the intermediate image P to a maximum of 0.9 times, and anenlargement of the second stereoscopic angle α2 in the intermediateimage P in comparison to the first stereoscopic angle α1 in the objectplane 1 to at least 1.1 times is achieved. In this respect, thestereoscopic angles α1 and α2, respectively, are defined by thestereoscopic basis of the imaging system 26.

The second subsystem T2, of the imaging system 26 also contains aplurality of optical lenses 16′ to 19′ and 16″ to 19″, in which theoptical imaging paths 2 a and 2 b are guided separately, in contrast tothe first subsystem T1. This means that the optical lenses 16′ to 19′and 16″ to 19″, 16′″ to 19′″ are respectively traversed by one opticalimaging path 2 a or 2 b, each.

The stereoscopic axes are defined by the respective centers of the two(stereoscopic) optical imaging paths 2 a and 2 b for an object point ofthe object that can be placed in the object plane 1, the object pointcorresponding to the center of the representation caused by themicroscope system. As an alternative to this object point it is alsopossible to directly use a point in the object plane 1 that correspondsto the center of the representation caused by the microscope system.This definition of the stereoscopic axes is best understood by referringto FIG. 1A and 1 b. In FIG. 1A beam bundles of the two (stereoscopic)optical imaging paths 2 a and 2 b for imaging one point in the objectplane 1 are shown, the point corresponding to the center of therepresentation caused by the microscope system. The central rays of thebeam bundles of these two optical imaging paths 2 a and 2 b define thetwo stereoscopic axes. In FIG. 1B only beam bundle 2 a, 2 a′, 2 a″, 2a′″ and 2 a″″ of only one optical imaging path are shown. In thisrespect, one beam bundle of the optical imaging path for therepresentation of one point of the object plane, corresponding to thecenter of the representation caused by the microscope system, isdesignated 2 a and represents the whole optical imaging path. Centralrays of this beam bundle 2 a can be used to define the stereoscopicaxes. However, the central rays of the boundary beam bundles 2 a′, 2 a″,2 a′″ and 2 a″″ of the optical imaging path, that are additionally shownin FIG. 1B, cannot be used to define the stereoscopic axes. In thisrespect, the optical lenses 16′ to 19′ and 16″ to 19″ of the secondsubsystem T2, due to the beam bundles guided therein, also define thecourse of the optical imaging paths 2 a and 2 b in the optical lenses 4,5, 6, 7, 8, 11, 13 and 14 of the first subsystem T1, and thus the courseof the stereoscopic axes.

Via the optical lenses 16′ to 19′ and 16″ to 19″ of the second subsystemT2 and the seventh and eighth lenses 13 and 14 of the second set G2 ofthe first subsystem T1 the intermediate image P is imaged in a magnifiedway. As the object plane 1 is imaged in a demagnified way into theintermediate image P, and/or the second stereoscopic angle α2 in theintermediate image P is enlarged in comparison to the first stereoscopicangle α1 in the object plane 1, this magnified representation of theintermediate image P in the second subsystem T2 can be achieved byoptical elements such as lenses having small diameters and smallrelative distances from one another along the respectively guidedoptical imaging paths 2 a and 2 b. Consequently, the imaging system 26of the microscope system according to the invention has an especiallycompact structure.

FIG. 3 shows in an exemplary way a comparison of sizes between lenses16′ to 19′ of the second subsystem T2 of the microscope system accordingto the invention (at the top of the Figure) with corresponding lenses ofa conventional microscope system (at the bottom of the Figure).

As indicated in FIG. 1B, each optical imaging path 2 a and 2 b of thesecond subsystem T2 may each further contain two optical lenses 20′ and21′ and one camera-adapter 22′ for a digital camera (not shown in FIG.2A or 2 b) for generating image data. Alternatively, two separatedigital cameras, or else one stereoscopic camera, may be provided forboth optical imaging paths 2 a, 2 b.

According to an alternative embodiment that is not separately shown, atube having ocular optics, for direct visual observation by a user, maybe provided for each optical imaging path 2 a and 2 b of the secondsubsystem T2 instead of optical lenses 20′ and 21′, as well as of thecamera-adapted 22′.

According to a further aspect of the present invention, according to afirst embodiment shown in FIGS. 1A and 1B, the first lens 4 isdisplaceable relative to the second lens 5 along the optical axis A andthus along the optical imaging paths 2 a and 2 b guided therein, and thethird lens 6 is displaceable relative to the fourth lens 7 along theoptical axis A and thus along the optical imaging paths 2 a and 2 bguided therein, to vary a distance of the object plane 1 to the imagingsystem 26 of the microscope system, and thus to vary a working distanceand a magnification of the representation of an object which can beplaced in the object plane 1. At the same time it is automaticallyguaranteed, by suitable choice of the system data of these opticallenses 4, 5, 6 and 7 of the first optical subsystem, that the opticalimaging paths 2 a and 2 b intersect in the object plane including thestereoscopic angle α1 that is different from zero, even after thedisplacement of the lenses 4, 5, 6 and 7.

In addition, three distances between four lenses 16′ to 19′ and 16′ to19″ of the second subsystem T2 that are arranged along one commonoptical axis in each of the respective optical imaging paths 2 a and 2b, respectively, are displaceable relative to one another along theoptical axis and thus also along the respective common optical imagingpaths 2 a and 2 b guided therein, to vary a magnification of therespective representation caused by the second subsystem T2 in therespective optical imaging paths 2 a and 2 b.

Instead of displaceable lenses, optical elements with variablerefraction force, such as liquid lenses may be used as an alternative.

Consequently, the microscope system according to the invention, as shownin FIGS. 1A and 1B, comprises two zoom systems that are arranged inseries, wherein one zoom system is provided by optical lenses of thefirst subsystem T1 and the second zoom system is provided by opticallenses of the second subsystem T2, and wherein the effects thereofcomplement one another.

The optical system data of the stereoscopic microscope shown in FIG. 1Aare as follows:

Radius Thickness Free Diameter Surface [mm] [mm] Medium [mm]Camera-adapter/tube 19″c 28.930 12.00 1.2 LAFN7 19″b 15.052 11.8 3.0NPSK53 19″a −144.79 11.5 22.68 . . . 1.0 2 Air 18″c −35.928 10.0 1.2NBAF4 18″b 9.9568 10.0 2.0 NSF6 18″a 19.467 9.5 11.5 . . . 11.5 Air 17″c−19.467 9.5 2.0 NSF6 17″b −9.9568 10.0 1.2 NBAF4 17″a 35.928 10.5  1.02. . . 22.68 Air 16″c 144.79 11.5 3.0 NPSK53 16″b −15.052 11.8 1.2 LAFN716″a −28.930 12.0 20.0  Air 14c 102.55 34.0 3.0 LAFN7 14b 50.047 34.06.0 NFK51 14a −197.88 34.0 1.0 Air 13b 52.089 34.0 4.0 NFK51 13a 306.5534.0 20.0  Air 12 Plane Mirror  65.805 Air 11b Plane 30.0 4.0 LAFN7 11a−116.05 30.0  38.195 Air 10 Plane Mirror 44.0  Air  9 Plane Mirror 23.0 Air  8b −392.46 48.0 6.0 NFK51  8a −75.151 48.0 1.0 Air  7c 273.58 48.08.0 NFK51  7b −68.282 48.0 4.0 LAFN7  7a −151.48 48.0  2.0 . . . 18.0Air  6c 238.24 48.0 7.0 NPSK53  6b −93.039 48.0 4.0 SF56A  6a −332.2848.0 0.1 Air  5b 107.96 46.0 5.0 NSK16  5a Plane 46.0 16.5 . . . 0.5 Air  4c Plane 45.0 3.0 NSSK8  4b 43.717 42.0 5.0 NSF6  4a 66.970 40.022.0  Air  3 Plane Mirror 224.0 . . . 424.0 Air Object plane

In FIGS. 1A and 1B the lenses 4, 5 and 6 form a tele-varioscope.However, a retrofocus-varioscope may be used as an alternative. Acorresponding structure is schematically shown in FIG. 4.

The microscope system according to the first preferred embodimentfurther provides a secondary optical path 24 that traverses the firstmirror surface 3 of the first deflecting element in a central area. Thiscentral area is preferably located between cross-sectional surfaces ofrays of the optical imaging paths 2 a and 2 b. This can e.g. beguaranteed if the optical lenses of the first subsystem T1 cause arepresentation of pupils in the range of the first mirror surface. Tothis end the first mirror surface 3 has a cutout 25, which is shown inFIG. 1B. As an alternative to the provision of a cutout, it is alsosufficient if the first mirror surface 3 provides at least in a partialarea a transparence for radiation of the secondary optical path 42 thatis higher than a transparence for a radiation of the optical imagingpaths 2 a and 2 b. Alternatively, the integration of the secondaryoptical path 24 may be achieved in another way. Thus the microscopesystem shown in FIG. 1A provides a 0°-illumination for an object thatcan be placed in the object plane 1.

In FIG. 1A the secondary optical path 24 is provided by illuminationoptics 30 of an illumination system, wherein the illumination systemfurther comprises a radiation source 23. This illumination system is notpart of the imaging system 26.

Alternatively, in addition, or as an alternative to the illuminationsystem comprising the illumination optics 30 and the radiation source23, an infrared-imaging system (not shown in the Figure) having aninfrared imaging optics and an infrared camera may be provided, whereinthe infrared imaging optics provides the secondary optical path 24.Furthermore, also in addition, or as an alternative to the illuminationsystem, a laser (not shown in the Figure) having a radiation guidancesystem (also not shown in the Figure) providing the secondary opticalpath 24 may be provided. Such a laser allows, for example, a therapeuticuse for cancer treatment.

Furthermore, a beam splitter (also not shown in the Figures) may beprovided which splits the optical imaging paths 2 a and 2 b by geometricor physical beam splitting. If this beam splitter is arranged betweenthe first subsystem T1 and the second subsystem T2, and thus in theregion of the second afocal interface A2, a co-observation tube can beprovided, this co-observation tube being freely pivotal and having amagnification that can be independently varied to a large extent. Aco-observation tube that is freely pivotal accounts best for theergonomic requirements of a user of the microscope system.

In the first preferred embodiment described above, the first, second,third and fourth deflecting elements are each optical mirrors.Alternatively, as an example, the deflection elements may be prisms,each having at least one mirror surface. Furthermore the first, second,third and fourth deflecting elements may optionally provide separatemirror surfaces for deflection of the optical imaging path 2 a and 2 b.

Alternatively, it is even possible to abstain totally or partially froma deflection of the optical imaging paths 2 a and 2 b. It is evenpossible that the optical imaging path is only deflected, once, twice,or three times, for example.

However, in consequence the structure of the microscope system may besignificantly extended. Regardless of the alternatives used, themicroscope system according to the present invention still comprises astructure that is more compact than a microscope system of the prior artthat is folded in the same way. The reason for this is that the secondsubsystem T2 of the microscope system according to the invention is morecompact than, but provides the same total magnification of themicroscope systems as a corresponding second subsystem of a conventionalmicroscope system. As a further alternative it is even possible todeflect the optical imaging paths 2 a and 2 b more often than fourtimes.

The microscope system according to the first preferred embodiment isespecially suited for use as a surgical microscope, as the imagingsystem 26 has an especially small overall height and an especially smallconstruction volume.

FIG. 1B schematically shows a perspective view to illustrate the truespatial arrangement of basic elements of the imaging system 26 of themicroscope system according to the first preferred embodiment (incontrast to the arrangement that is unfolded in one plane, as in FIG.1A). For better clarity, only one optical imaging path 2 a is shown inFIG. 1B, and the illumination system is also not shown.

It is a disadvantage of microscope systems as described above in whichit is possible to adjust at least one of a magnification of therepresentation and a working distance by displacing optical lenses, thatthe variation of the working distance, that is considered to be veryadvantageous by a user, is usually accompanied with a discrepancybetween the focal length and the respective working distance. Forexample, the focal length in a tele-varioscope system is significantlylarger than the working distance, whereas the focal length issignificantly shorter than the working distance in aretrofocus-varioscope system.

To solve this problem the trifurcated varioscope system shown in FIGS. 5and 6 is proposed. This trifurcated varioscope system has three opticalcomponents 51,52,53, and 61,62,63, that respectively are arranged inseries, which are sequentially traversed by the at least one opticalimaging path.

In FIGS. 5 and 6, the first optical components 51,61 respectively areeach formed by one optical lens. Further, the second optical components51,62 respectively each are formed by two optical lenses that arestationary relative to one another.

In FIG. 5 two optical lenses that are separated from each other by aconstant distance also form the third optical component 53, whereas inFIG. 6 the third optical component 63 is formed by only one opticallens.

By well defined simultaneous variation of air distances d1 and d2between the three optical components 51,52,53, and 61,62,63,respectively, a varioscope system having the properties of a mainobjective having a fixed focal length is provided, to guarantee anadjustment of the focal length to a working distance AA from an objectplane 1 even after a variation of the working distance.

The system data of the retrofocus-varioscope system shown in FIG. 5 areas follows:

Radius Thickness Free Diameter Surface [mm] [mm] Medium [mm] 51c 80.96320.0 4.0 NSSK8 5b −45.484 20.0 2.0 NSF6 51a −123.82 20.0 8.2 . . . 1.2Air 52e −1524.4 20.0 3.0 SF57 52d −40.485 20.0 2.0 NPSK53 52c 37.66820.0 3.0 Air 52b −34.879 20.0 2.0 NPSK3 52a 172.34 20.0 7.7 . . . 1.7Air 53e 209.32 32.0 4.0 NPSK53 53d −55.334 32.0 0.1 Air 53c 70.408 32.07.0 NPSK53 53b −47.754 32.0 3.0 NSF6 53a −564.00 32.0 200 . . . 400Object

Suitable distances d1 and d2 between the optical components 51,52 and 53of the retrofocus-varioscope system shown in FIG. 5 are quoted in thefollowing table:

AA d1 d2 [mm] [mm] [mm] 200 8.16 7.74 300 3.51 3.56 400 1.18 1.72

The system data of the tele-varioscope system shown in FIG. 6 are asfollows:

Radius Thickness Free Diameter Surface [mm] [mm] Medium [mm] Zoom 61c−119.41 25.0 3.0 SF57 61b −69.972 25.0 2.0 NBAF52 61a 126.85 25.0 19.9 .. . 5.8  Air 62e 304.82 32.0 6.0 NPSK53 62d −31.227 32.0 3.0 SF57 62c−56.307 32.0 0.1 Air 62b 66.072 32.0 4.0 NPSK53 62a −411.61 32.0 7.0 . .. 1.1 Air 63c −276.18 32.0 3.0 NSSK8 63b 27.297 32.0 4.0 NSF6 63a 47.86432.0 200 . . . 400 Air Object

The distances d1 and d2 between the optical components 61,62, and 63 forspecified working distances AA from the object plane 1 are as follows:

AA d1 d2 [mm] [mm] [mm] 200 19.88 7.03 300 10.52 3.26 400 5.84 1.06

In summary, the above solution that has been described with reference toFIGS. 5 and 6 differs from conventional varioscope systems in that forvariations of the working distance two air distances d1 and d2 betweenthe three optical components 51, 52 and 53, and 61, 62 and 63respectively, are varied, wherein in conventional varioscopes only oneair distance must be varied for variation of the working distance. Thevarioscope systems described above with constant focal length do nothave an as compact structure as conventional varioscope systems workingaccording to the known tele-principle or retrofocus-principle. However,this disadvantage is compensated for to a large extent by the foldedstructure of the microscope system itself, and is more than compensatedfor by the achieved advantages of the varioscope system having constantfocal length. Additionally they provide an up to now unknown solution tothe requirement to overcome the discrepancy between working distance andfocal length that exists with conventional varioscope systems.

Consequently, the varioscope system having constant focal length that isshown in FIGS. 5 and 6 is especially suited for the microscope systemdescribed above according to the first preferred embodiment of thepresent invention.

In the following a second embodiment according to the present inventionis described with reference to FIG. 7. In FIG. 7, an optical paththrough an arrangement of optical elements of an imaging system 26′ ofthe microscope system is schematically shown, unfolded in one plane. Thestructure of the microscope system according to the second embodimentcorresponds in basic parts to the structure of the microscope systemaccording to the first embodiment, described in detail above.Consequently, only the differences between the first and secondembodiment will be described in detail below.

The microscope system according to the second embodiment also comprisesan imaging system 26′, for imaging an object (not shown) that can beplaced in an object plane 1. In this respect, the imaging system 26′provides two pairs of optical imaging paths 2 a,2 b and 2 c,2 d. Theimaging system 26′ consists (similarly as in the first embodimentdescribed above) of a first subsystem T1′ having multiple optical lenses4 to a and 11 in which the optical imaging paths 2 a to 2 d are commonlyguided, and a second subsystem T2′ having multiple optical lenses 16′ to21′, 22′, 16″ to 21″,22″, 16′″ to 21′″,22′″ and 16″″ to 21″″, 22″″, inwhich the optical imaging paths 2 a to 2 d are guided separately. Inthis embodiment lenses of the first and second subsystems T1′ and T2′are also displaceable relative to one another to adjust the workingdistance and vary the magnification of the representation, respectively.A further description of these elements is avoided.

It is essential in the second embodiment that is shown in FIG. 7 that nodeflecting elements for deflecting the optical imaging paths 2 a to 2 dare provided. Only the optical imaging paths 2 c and 2 d are folded in afreely pivotal beam splitter 15, to be separated from the opticalimaging paths 2 a and 2 b and to provide ergonomic adaptation of theoptical imaging paths.

FIG. 7 additionally shows two digital cameras 31′ and 31″ that generateimage data by using the rays guided by the optical imaging paths 2 a and2 b. Furthermore, two ocular optics 32′″ and 32″″ are provided fordirect visual observation of radiation guided by the optical imagingpaths 2 c and 2 d by an observer.

In the second embodiment integration of the zero-degree illumination isprovided by an illumination mirror, that is arranged in a pupil plane ofthe optical imaging paths 2 a to 2 d between cross-sectional surfaces ofradiation guided by the optical imaging path 2 a to 2 d.

The microscope system according to the second embodiment can also becombined with a varioscope system having a constant focal length asshown in FIGS. 5 and 6.

In summary, a microscope system for imaging of an object that can beplaced in an object plane of the microscope system is proposed, whichmicroscope system has an especially compact structure for a desiredtotal magnification due to at least one of a demagnified representationof the object plane into an intermediate image and an increasedstereoscopic angle in the intermediate image in comparison to thestereoscopic angle in the object plane.

1. A microscope system for imaging of an object that can be placed in anobject plane of a microscope system, the microscope system comprising:an imaging system having several optical elements for providing at leastone optical imaging path, wherein the several optical elements comprisea plurality of optical lenses through which the optical imaging pathpasses in sequence and which image the object plane into an intermediateimage, wherein the optical lenses are configured in such a way that therepresentation of the object plane is imaged into the intermediate imagedemagnified to a maximum of 0.9 times and preferably to a maximum of 0.8times, and further preferably to a maximum of 0.6 times, and especiallypreferably to a maximum of 0.5 times.
 2. The microscope system accordingto claim 1, wherein the several optical elements of the imaging systemprovide at least a pair of optical imaging paths that include a firststereoscopic angle in the object plane, wherein the optical imagingpaths include a second stereoscopic angle in the intermediate image, andwherein a ratio of the first stereoscopic angle in the object plane tothe second stereoscopic angle in the intermediate image is smaller than0.9 and preferably smaller than 0.8 and especially preferably smallerthan 0.6.
 3. Microscope system for imaging an object that can be placedin an object plane of a microscope system, the microscope systemcomprising: an imaging system having several optical elements forproviding at least one pair of optical imaging paths that include afirst stereoscopic angle in the object plane, wherein the severaloptical elements comprise a plurality of optical lenses through whichthe at least one pair of optical imaging paths passes in sequence, andwhich optical lenses image the object plane into an intermediate image,and wherein the optical imaging paths include a second stereoscopicangle at the intermediate image, wherein a ratio of the firststereoscopic angle in the object plane to the second stereoscopic anglein the intermediate image is smaller than 0.9 and preferably smallerthan 0.8 and especially smaller than 0.6.
 4. The microscope systemaccording to claim 3, wherein the optical lenses are commonly traversedby the optical imaging paths, and wherein the optical imaging paths areguided in the lenses in such a way that the intermediate image isarranged in-between two regions in which a distance of stereoscopic axesof the optical imaging paths from an optical axis defined by the lensesrespectively is a maximum.
 5. The microscope system according to claim3, wherein the at least one optical imaging path is guided in the lensesin such a way that the intermediate image is arranged in-between tworegions in which a diameter of a beam bundle guided in the at least oneoptical imaging path is a maximum.
 6. The microscope system according toclaim 4, wherein a first set of optically effective surfaces of lensesis arranged in-between the intermediate image and the first of the tworegions in which at least one of a distance of stereoscopic axes of theoptical imaging paths from the optical axis and a diameter of a beambundle guided in the at least one optical imaging path, respectively, isa maximum, wherein the first region is arranged between the intermediateimage and the object plane, wherein a second set of optically effectivesurfaces of lenses is arranged in-between the intermediate image and thesecond one of the two regions, and wherein a third set of opticallyeffective surfaces of lenses is arranged in-between the first region andthe object plane.
 7. The microscope system according to claim 6, whereina ratio of the total focal length of the optically effective surfaces ofthe first set to the total focal length of the optically effectivesurfaces of the second set is at least 1.1 and preferably at least 1.2and further preferably at least 1.4.
 8. The microscope system accordingto claim 6, wherein a ratio of the total focal length of the opticallyeffective surfaces of the first set to the total focal length of theoptically effective surfaces of the third set is between 0.2 and 0.6 andpreferably between 0.3 and 0.5 and further preferably 0.4.
 9. Themicroscope system according to claim 6, wherein a ration of the totalfocal length of the optically effective surfaces of the second set tothe total focal length of the optically effective surfaces of the thirdset is between 0.1 and 0.6 and preferably between 0.2 and 0.5 andespecially preferably 0.3.
 10. The microscope system according to claim4, wherein a ratio of the respective distances of stereoscopic axes ofthe optical imaging paths from the optical axis in the first region tothe respective distances of stereoscopic axes of the optical imagingpaths from the optical axis in the second region is a maximum of 1.1 andpreferably a maximum of 1.2 and especially preferably a maximum of 1.4.11. The microscope system according to claim 4, wherein the lenses focusthe optical imaging paths at least in one of the regions to infinity, inwhich regions at least one of a distance of stereoscopic axes of theoptical imaging paths from the optical axis and a diameter of a beambundle guided in the at least one optical imaging path is maximized. 12.The microscope system according to claim 1, wherein the imaging systemcomprises a first, second, third and fourth mirror surface fordeflection of the at least one optical imaging path, and wherein the atleast one optical imaging path is deflected in sequence by the firstmirror surface, the second mirror surface the third mirror surface, andthe fourth mirror surface.
 13. The microscope system according to claim12, wherein the first mirror surface and the fourth mirror surfaceinclude an angle of between 80° and 100° and preferably 90° relative toone another, as well as wherein the second mirror surface and the thirdmirror surface include an angle of between 80° and 100° and preferably90° relative to one another, and wherein the third mirror surface andthe fourth mirror surface include an angle of between 80° and 100° andpreferably 90° relative to one another.
 14. Microscope system accordingto claim 12, wherein the imaging system provides at least a pair ofoptical imaging paths that include a stereoscopic angle in the objectplane, and wherein the imaging system has a first subsystem, the firstsubsystem comprising a plurality of optical lenses which are commonlytraversed by the two optical imaging paths of the at least one pair ofoptical imaging paths.
 15. The microscope system according to claim 14,wherein at least one of the second and third and fourth mirror surfaceis arranged between optical lenses of the first subsystem.
 16. Themicroscope system according to claim 15, wherein at least two lenses(4,5,6) of the first subsystem are displaceable relative to one anotheralong the optical imaging paths guided therein.
 17. The microscopesystem according to claim 1, wherein the imaging system has a secondsubsystem, which second subsystem comprises a plurality of opticallenses that are respectively traversed by only one optical imaging pathof the at least one pair of optical imaging paths.
 18. The microscopesystem according to claim 17, wherein at least two lenses of the secondsubsystem are displaceable relative to one another along one commonoptical imaging path.
 19. Microscope system for imaging of an objectthat can be placed in an object plane of a microscope system, whereinthe microscope system comprises: an imaging system for providing atleast one pair of optical imaging paths that include a stereoscopicangle (in the object plane, wherein the imaging system has a firstsubsystem that comprises a plurality of optical lenses, which lenses arecommonly traversed by both optical imaging paths of the at least onepair of optical imaging paths, and wherein the imaging system has asecond subsystem comprising a plurality of optical lenses, which lensesrespectively are traversed by only one optical imaging path of the atleast one pair of optical imaging paths, wherein at least two lenses ofthe first subsystem and at least two lenses of the second subsystem aredisplaceable relative to one another along one common optical imagingpath to respectively vary a magnification of the representation of theobject that can be placed in the object plane.
 20. The microscope systemaccording to claim 1, wherein the microscope system further comprises alighting system having an optical lighting path for illuminating theobject plane.
 21. The microscope system according to claim 1, whereinthe microscope system is a stereomicroscope and preferably a surgicalmicroscope.
 22. The microscope system according to claim 3, wherein theimaging system comprises a first, second, third and fourth mirrorsurface for deflection of the at least one optical imaging path, andwherein the at least one optical imaging path is deflected in sequenceby the first mirror surface, the second mirror surface, the third mirrorsurface, and the fourth mirror surface.
 23. The microscope systemaccording to claim 22, wherein the first mirror surface and the fourthmirror surface include an angle of between 80° and 100° and preferably90° relative to one another, as well as wherein the second mirrorsurface and the third mirror surface include an angle of between 80° and100° and preferably 90° relative to one another, and wherein the thirdmirror surface and the fourth mirror surface include an angle of between80° and 100° and preferably 90° relative to one another.
 24. Themicroscope system according to claim 19, wherein the imaging systemcomprises a first, second, third and fourth mirror surface fordeflection of the at least one optical imaging path, and wherein the atleast one optical imaging path is deflected in sequence by the firstmirror surface, the second mirror surface, the third mirror surface, andthe fourth mirror surface.
 25. The microscope system according to claim24, wherein the first mirror surface and the fourth mirror surfaceinclude an angle of between 80° and 100° and preferably 90° relative toone another, as well as wherein the second mirror surface and the thirdmirror surface include an angle of between 80° and 100° and preferably90° relative to one another, and wherein the third mirror surface andthe fourth mirror surface include an angle of between 80° and 100° andpreferably 90° relative to one another.